1. Field
Embodiments of the invention relate to the field of network processing; and more specifically, to load balancing IPTV channels over aggregate links.
2. Background
Internet Protocol Television (IPTV) may be transmitted through an Ethernet network (e.g., IP based broadcast TV). Typically a source of the IPTV is coupled with a headend router, which is typically coupled with an Internet Protocol/Multiprotocol Label Switching (IP/MPLS) network. A label switched network is typically coupled with the IP/MPLS network. Each network element in the label switched network typically acts as a Provider Edge (PE) network element for one or more access network elements that replicate IP traffic (e.g., digital subscriber line access multiplexer (DSLAM)). The PE network elements in the layer 2 label switched network are each coupled with one or more MPLS pseudowires. Each pseudowire may, and often does, carry multiple IPTV channels.
The label switched network is typically a layer 2 network (layer 2 is the data link layer as defined in the Open Systems Interconnection Basic Reference Model (OSI Model) (ISO/IEC 7498-1, Nov. 15, 1994). Typical network elements (e.g., PE network elements) in the label switched network do not perform processing beyond layer 2 or beyond MPLS processing (sometimes referred to as layer 2.5). Thus, typical network elements in the label switched network do not perform layer 3 processing (layer 3 is the network layer as defined in the OSI model) (e.g., determining routing decisions based on layer 3 IP addresses). Typical network elements in the label switched network base their forwarding decisions on MPLS labels encapsulated in the IPTV packets.
Customer premise equipment (CPE) (e.g., set-top boxes (STB)) issue Internet Group Management Protocol (IGMP) (defined in RFC 1112, RFC 2236, and RFC 3376) messages that indicate request for membership into a group. Each group corresponds to an IPTV channel and is identified by a multicast group IP address. In addition, all members of a certain group receive IPTV channel data in form of IP packets.
The physical links between the network elements in the layer 2 label switched network may be aggregate links conforming to clause 43 of the Institute of Electrical and Electronics Engineers (IEEE) standard 802.3 (Dec. 9, 2005) (informally known as the 802.3ad Link Aggregation standard). An aggregate link includes multiple physical member links. Each physical member link may have different characteristics (e.g., differing amounts of bandwidth, etc.). Aggregate links are used to protect against link failures (e.g., line card failures) by providing redundancy (e.g., if one member link fails, another member link may be used). In addition, aggregate links provide more bandwidth across physical endpoints (e.g., multiple member links may be used to transmit traffic concurrently). Each pseudowire in the layer 2 label switched network typically is transmitted over these aggregate links. Thus, packets from a single pseudowire may be transmitted from one PE network element to another PE network element over multiple physical links.